Acne vulgaris is a dermatological disorder prevalent in adolescence. It appears most commonly on the face and trunk of the patient. The basic lesion of acne is the comedo (or "blackhead") of a pilosebaceous follicle. In its mildest form, only a few comedones are present, but in more severe forms, many severe, persistent comedones are present. Severe acne can cause permanent scarring.
Acne occurs when there is a filling up of the follicle with a rather tough, keratinous material. These impactions of horny material are the whitehead and blackhead. As a result of bacterial growth in these horny impactions, the follicle may rupture, initiating the inflammatory phase of the disease, which takes the form of pustules, papules, cysts and nodules.
Over the years, there have been a variety of theories regarding the cause, prevention and treatment of acne. Dr. F. Lyons reported at the 1982 annual meeting of the European Society of Dermatological Research the results of a study that shows a direct relationship between excess sebum secretion and acne. This is believed to provide important information for the monitoring and management of acne, and a great impetus for studies of the secretion patterns of sebaceous glands.
Several methods have heretofore been used to collect and quantify the secretions from sebaceous glands. In one such method, a test area on the skin surface is irrigated with a suitable lipid solvent. In another, an absorbent material such as a cigarette paper or cotton is applied on the skin surface for a specified period of time. Subsequent applications of well-known techniques such as chromotography, solvent extraction and distillation permit quantification of the amount of sebum collected. However, these techniques involve pooling of the sebum output and do not provide information regarding the relative concentration or output of sebaceous glands in different skin areas. Another recently introduced method involves absorbing sebum onto a frosted glass plate and then electronically measuring the change in light scattering.
The present invention, however, provides a more satisfactory means for analyzing sebum output at different skin sites in that it involves the use of a comformable film that, in one application, can provide, in seconds, a convenient broad evaluation of the degree of sebaceous gland activity, and, in another application, can be preserved as a permanent record and used for semi-quantitative estimation without resort to expensive instrumentation or complicated analysis. This permits more rapid diagnosis as well as more focused treatment. In fact, in one aspect of the invention, the same type of device as is used for diagnosis can also be applied to the skin, with or without an active ingredient incorporated therein, and used to treat or prevent outbreaks of acne or other conditions associated with production (or secretion) of sebum by sebaceous glands.
In U.S. Pat. No. 3,449,080, issued June 10, 1969, there is described a diagnostic device for determining the level of chloride in the body sweat of subjects, which device comprises a bibulous paper impregnated with a weakly acid or weakly basic ion exchange resin and a suitable pH indicator such as phenolphthalein. The device is applied to the forehead of a subject, such as a perspiring child. When the device changes color upon being wetted with the subject's perspiration, it is removed and the color compared to a previously prepared color comparison chart. A similar device is described in U.S. Pat. No. 3,552,929, issued Jan. 5, 1971. In this device, there are a plurality of distinct regions which contain different, predetermined amounts of halide-sensitive reagent. A related device is shown in U.S. Pat. No. 4,163,039, issued July 31, 1979, this device being designed to have the impregnated indicator show a color change only when the concentration of sodium or chloride ion in a subject's sweat is at least 50 meq/l. This device also comprises a perforated transparent envelope through which the sweat is absorbed.
These devices, while having some similarity to that of the present invention, are not suitable for the purposes thereof since they depend on color change caused by an ionic reaction, whereas such ionic content as may be present in sebum is essentially irrelevant to the diagnostic purpose of the present invention. Moreover, these references fail to disclose or suggest either the presence or function of the microporous film of the present invention, or the need, when preparing the adhesive coated film of the invention, to provide a coating of adhesive that will not itself migrate into the pores of the microporous film but that permits the passage of sebum therethrough so that the sebum is absorbed into the pores of the film.